Method for supplying oxygen to a diver

ABSTRACT

Method and apparatus for supplying breathing gas to a person in a pressurized environment when a given dose of gas is recirculated in a closed breathing system a predetermined number of times and is then expelled and replaced with a new dose. The number of rebreaths is found as a function of the pressure of the environment.

United States Patent Eklund [451 Aug. 8, 1972 [54] METHOD FOR SUPPLYING OXYGEN TO A DIVER Inventor: Erik Eklund, Karjaa, Finland Filed: Feb. 20, 1970 Appl. No.: 13,161

30 Foreign Application Priority om Feb. 25, 1969 Finland .....583/69 US. Cl ..l28/l42, 128/ 142.2 Int. Cl. ..A62b 7/02 Field of Search....128/140 R, 142, 142.2, 142.4,

References Cited UNITED STATES PATENTS 3,480,011 11/1969 Costeau ..128/142.2

CO2 ABSORBER 2,168,695 8/1939 Asari 128/142 2,296,496 9/ 1942 Bortin ..128/203 2,830,583 4/ 1958 Finney, .lr 128/ 142 Primary Examiner-William E. Kamm Attorney-Kurt Kelman ABSTRACT Method and apparatus for supplying breathing gas to a person in a pressurized environment when a given dose of gas is recirculated in a closed breathing system a predetermined number of times and is then expelled and replaced with a new dose. The number of rebreaths is found as a function of the pressure of the.

environment.

9 Clairm, 1 Drawing Figure i BREATHlNG BAG n PRESSURE REGULATOR AIR CYLINDER l DEMAND VALVE MOUTH MASK Garrahan ..l28/l42 PATENTEDAUB 8 I972 CO2 ABSORBER BREATHING BAG @CH ECK VALVE NOSE MASK PRESSURE REGULATOR METHOD FOR SUPPLYING OXYGEN TO A DIVER The invention relates to a method for supplying oxygen to a diver.

As it is known, air consists of oxygen and nitrogen, the quantities of which being about 20 percent and 80 percent or, when expressed in terms of partial pressures, 150 mm Hg and 610 mm Hg in a normal pressure.

A human being utilizes oxygen during breathing so that only about 5 percent of the entire air quantity and about 25 percent of the oxygen quantity is really used. This is the situation at normal atmospheric pressure. The pressure of gas, supplied for breathing at diving, has to be the same as the outer pressure. For example in a water depth of meters the outer pressure is 1,5 20 mm Hg. The partial pressure of the oxygen which is contained in the air supplied for breathing, is then 300mmHg.'Ihediveruses30mmHgofthisinany one breath. While the depth increases, the oxygen need of the body remains constant, in other words, this same partial pressure of oxygen, 30 mm Hg, is always needed irrespective of depth. It is known from experience that the optimal amount of oxygen at normal pressure is between the limits 152 mm Hg and 456 mm Hg. This corresponds to 20-60 percent oxygen at normal pres sure.

For longer dives, the maximum limit is, however, currently fixed at 1,520 mm Hg. Going below the minimum limit causes unconsciousness and exceeding the maximum limit causes oxygen poisoning. Oxygen may be supplied to a diver under the above-stated general conditions in two alternative ways:

According to the first way compressed-air apparatus is used; this involves, however, the inconvenience that the contents of the pressure chambers which constitute 95 percent of the apparatus and the waste air must increase in direct proportion to the increasing depth. This means in practice heavy devices, large waste and a shortened diving time.

According to the second way pure oxygen is used: it is rebreathed and carbon dioxide is absorbed between the lungs and the breathing bag. The used oxygen is replaced by means of an oxygen bottle. The oxygen is actually utilized up to almost 100 percent but this involves the inconvenience that the diving depth is confined to about 10 meters. Among these devices a socalled half-closed modification, is known whereby the diving depth is increased to some extent. In this latter case a gas composition is used instead of oxygen; this composition contains 40-70 percent of oxygen, the rest being a protective gas, for example helium.

It is the object of the present invention to eliminate the inconveniences explained briefly above and to bring about a better method and apparatus for supplying oxygen. According to the invention the supplying of compressed air is arranged in doses, intended for circulation and rebreathing, with the length of rebreathing dependent on the depth. The limits of the oxygen dose to be rebreathed are then preferably 152 and 1,520 mm Hg. The carbon dioxide is absorbed from the dose to be rebreathed by means of some filter known as such, for example LiOH absorption filter. Y

The drawing diagrammatically illustrates practice of the present invention.

The invention is described in greater detail as follows. Starting with the fact that 30 mm Hg is consumed at one breathing phase and that the minimum limit is 150 mm, the following table is obtained:

d. Total volume consumed from the container in liters according to the old method e. Total volume consumed from the container in liters according to the new method 20 f. Efficiency coefficient d/e l 5.55 14 50 g. Coeficient of lengthening tlivi3 time 51 2.78

h. Supply frequency from the presure bottle per 100 breaths 100 18 10 The table has been drawn up under the supposition that on the surface of water 1 liter is 'needed for a breath, the volume of 100 breaths being 100 liters and I the diving time 35 minutes. The table indicates that the saving of air is very great, in addition to which the diving time increases considerably in proportion to the increasing diving depth. This is the more significant factor, as in connection with an ordinary compressed-air apparatus the diving time lengthens while the diving depth is increasing. The following table illustrates diving times.

The values for a 40 percent oxygen composition are given below. It is not advisable with this mixture to exceed the diving depth of 40 meters, as the partial pressure of oxygen reaches the value 1,550 mm Hg at the beginning of a rebreathing phase.

lengthening diving time h. Supply frequency from the pressure bottle per 100 breaths The values for a 50 percent oxygen composition are given below. It is not advisable with this mixture to 50 exceed the diving depth of 30 meters, as the partial pressureof oxygen reaches the value 1,520 mm Hg.

a. Diving depth in g. Coefficient of lengthening diving time 9.1

h. Supply frequency from the preaure bottle per 100 breaths Diving depth 7 meter Diving time according to old method 'min.

Diving time according to new method min. H

This indicates that in comparison with an ordinary method considerably longer diving times are obtained by the method according to the invention.

Although the invention has been described in connection with compressed-air devices, itis obvious that the method can be applied equally in connection with a composition of oxygen and any other inert protective gas. The ratio of protective gas and oxygen may differ from the content ratio of oxygen in air.

The invention can also be used, in diving with open equipment, with helmet devices and when a diver leaves a submarine.

The method according to the invention can be realized. by very simple equipment and it involves the special advantage that present compressed-air devices can be used when provided with suitable auxiliary devices.

In a simple case an ordinary compressed-air equipment is used which consists of a compressed-air bottle 10, pressure regulator valve 11, 12 and conventional demand valve prior to a mouthpiece 13. There is also a diving mask 14 to cover the nose, tubes l5, 16 leading from the mask to a breathing bag 17 of 3-5 liters first by way of a conventional check valve, then through a filter container 18 for absorbing the carbon dioxide. The compressed air arrives in the mouthpiece, from which it is inhaled through the mouth. Rebreathing takes place through the nose, from the mask to the bag and vice versa. This is continued until the calculated number of rebreaths is achieved, whereafter the dose is blown outv into water through the mouth and the mouthpiece. In this case the diver himself counts the number of rebreaths in'proportion to the diving depth.

A more advanced equipment may include a tactile organ for the pressure corresponding to the diving depth, a calculating device regulated by this and a valve controlled by this, which allows the compressed air to flow from the bottle into the rebreathing space in doses, with certain intervals in accordance with the invention. It is obvious that an appropriate guiding mechanism can be constructed electronically, whereat 4 it becomes inexpensive, takes up a small space and is g i riiie ri t ion isalso applicable to a-so-called closed system, wherein the pressure bottles contain pure oxygen. The inert gas, such as helium, is situated in a special small bottle. The oxygen and the protective gas are mixed in appropriate proportions. The gas is used at the end of a rebreathing phase is exhaled into a special bag, where the separation of the components may be carried out by filtration or by absorption of the oxygen rest so that only helium is left, and this is reused.

Iclaim: 1. A method of administering breathing gas to a diver underwater where the surrounding pressure of the water environment is greater than normal atmosphere pressure, said method comprising, supplying to the mouth of the diver a predetermined quantity of breathing gas equal to one breath, said breathing gas comprising a mixture of oxygen and inert gaseous material, circulating said gas in a closed system through successive breaths by way of the nose of the'diver, determining a maximum number of successive nasal rebreaths per supplied quantity of gas as a function of the pressure of said underwater environment, expelling said supplied gas after successive rebreaths by way of the mouth of the diver to the underwater environment after the predetermined number of rebreaths is reached, and resupplying to the mouth of the diver a succeeding predetemiined quantity of said breathing gas.

2. The method according to claim l,'includingthe step of maintaining the partial pressure of the oxygen portion of said gas between 152 1,520 mm Hg.

3. The method according to claim 1, including the step of removing carbon dioxide from the circulated 8 4. The method according to claim 1, wherein the ratio of oxygen to inert gaseous material approximates that in air.

5. The method according to claim 1, wherein the ratio of oxygen to inert gaseous material is greater than that in air.

6. The method according to claim 1, wherein inert gas is helium.

7. An apparatus for administering breathing gas to a diver underwater, said apparatus comprising in combination, a source of breathing gas comprising a mixture of oxygen and inert gaseous material, means for feeding to the mouth of the diver a predetermined quantity of breathing gas equal to one breath, a closed system having means for circulating successive breaths by way of the nose of the diver, and means operable at the termination of a predetermined number of nasal rebreaths by the diver to expell said gas after successive rebreaths by way of the mouth of the diver to the un-.

derwater environment.

8. The apparatus of claim 7 wherein said means for I feeding to the mouth of the diver is by way of a mouth mask, and said means for circulating successive breaths 

1. A method of administering breathing gas to a diver underwater where the surrounding pressure of the water environment is greater than normal atmosphere pressure, said method comprising, supplying to the mouth of the diver a predetermined quantity of breathing gas equal to one breath, said breathing gas comprising a mixture of oxygen and inert gaseous maTerial, circulating said gas in a closed system through successive breaths by way of the nose of the diver, determining a maximum number of successive nasal rebreaths per supplied quantity of gas as a function of the pressure of said underwater environment, expelling said supplied gas after successive rebreaths by way of the mouth of the diver to the underwater environment after the predetermined number of rebreaths is reached, and resupplying to the mouth of the diver a succeeding predetermined quantity of said breathing gas.
 2. The method according to claim 1, including the step of maintaining the partial pressure of the oxygen portion of said gas between 152 - 1,520 mm Hg.
 3. The method according to claim 1, including the step of removing carbon dioxide from the circulated gas.
 4. The method according to claim 1, wherein the ratio of oxygen to inert gaseous material approximates that in air.
 5. The method according to claim 1, wherein the ratio of oxygen to inert gaseous material is greater than that in air.
 6. The method according to claim 1, wherein the inert gas is helium.
 7. An apparatus for administering breathing gas to a diver underwater, said apparatus comprising in combination, a source of breathing gas comprising a mixture of oxygen and inert gaseous material, means for feeding to the mouth of the diver a predetermined quantity of breathing gas equal to one breath, a closed system having means for circulating successive breaths by way of the nose of the diver, and means operable at the termination of a predetermined number of nasal rebreaths by the diver to expell said gas after successive rebreaths by way of the mouth of the diver to the underwater environment.
 8. The apparatus of claim 7 wherein said means for feeding to the mouth of the diver is by way of a mouth mask, and said means for circulating successive breaths by way of the nose of the diver includes a nose mask.
 9. The apparatus according to claim 7, including absorption filter means for removing carbon dioxide from said circulating gas. 